The prior art is replete with references relating to low temperature condensation of coffee aroma frost. Aroma frost is a low temperature condensate of volatiles which escape during coffee processing, for example during roasting, grinding, steam distillation, extracting where it is employed, and dry distillation. These volatile constituents are often obtained by low temperature condensation of the escaping gaseous material, for example, at liquid nitrogen temperatures, by passing the escaping gas through a liquid nitrogen trap to yield a condensate which is referred to herein as an aroma frost. The aroma frost may be grinder gas frost, roaster gas frost, a dry distillation frost, a steam distillation frost, and the like. For examples of patents relating to methods of providing aroma frost, see for example, Lemonnier, U.S. Pat. No. 2,680,687, issued June 8, 1954; U.S. Pat. No. 3,021,218, Clinton et al., issued Feb. 13, 1962; Kline, U.S. Pat. No. 3,406,074; Mook et al., U.S. Pat. No. 3,035,922, issued May 22, 1962; and Kline et al., U.S. Pat. No. 3,535,118, issued Oct. 20, 1970.
However, once obtained, to be of value aroma frost must then be incorporated in a relatively stable manner into the coffee product whose roast and ground coffee aroma is desired to be increased. Usually this coffee product comprises an instant coffee because instant coffees are notably deficient in characteristic roast and ground coffee aroma. It has been found that little or no aroma value is obtained by using conventional coffee oil addition techniques in adding aroma frost to instant coffee products because nearly all of the aroma escapes before transfer to the jar. However, some aroma is retained providing the instant coffee has previously been sprayed or come in contact with in some other manner, coffee oil. For some reason, not precisely known, the coffee oil acts as a stabilizing factor in allowing a certain degree of retention of aroma frost aroma within the aromatized coffee product.
Still, even where aroma frost is first mixed with coffee oil and allowed to equilibrate in a manner such as is disclosed in co-pending application of Strobel entitled "Separating Aroma- and Flavor-Bearing Substrates Into Aroma and Flavor Concentrates," and then sprayed upon a coffee product, or where the aroma frost is incorporated into a highly stable purified coffee oil as is shown by copending U.S. Pat. application of Strobel, Ser. No. 126,305, filed Mar. 19, 1971 now U.S. Pat. No. 3,704,132, and thereafter sprayed upon instant coffee, it has been found that after spray-on addition the aroma intensity is significantly decreased.
Therefore, while condensation of aroma frost has heretofore been known, and while the value of utilizing coffee oil in combination with aroma frost has heretofore been known, it has not been heretofore appreciated that the manner of addition of the aroma-enriched coffee oil, or other suitable aroma carriers, to a coffee product whose aroma is desired to be increased is critical. It has now been found that where conventional methods of addition such as spraying, which is characteristically used in applying coffee oil to coffe products, are employed, the highly volatile constituents are stripped from the coffee oil and escape during the addition procedure. Consequently little benefit is obtained by utilizing the aroma-enriched oil as a coffee product aroma enhancer.
To summarize briefly, obtaining high quality aroma-enriched coffee oil or other carrier is only part of the story. The aroma transferred into the carrier is an extremely volatile material and if it is not carefully handled the previously entrapped volatiles can easily escape. Therefore, it often happens that by the time the aroma-enriched carrier is added to a coffee product whose aroma is desired to be increased, any benefit which might have been obtained is no longer present because highly aromatic volatile constituents have escaped.
Besides the importance of how aroma-enriched carriers, such as coffee oil, are added to a product whose aroma is desired to be increased, another factor has been found to be of particular importance where the coffee whose aroma is to be enhanced is an instant coffee. This second important factor is the coffee surface characteristics. If the instant coffee surface structure is such that the coffee has too many surface voids, the ability to retain added aroma upon aging in a sealed jar, without intensity loss or aroma character change, no matter what method of addition is employed, seems beyond reach.
Accordingly, it is an object of this invention to provide a method of addition of aroma-enriched carrier to coffee products whose roast and ground coffee aroma is desired to be increased, which does not strip away or otherwise allow escape of the highly volatile but high aroma-bearing constituents.
Still another object of this invention is to provide a commercially feasible method of adding aroma-enriched carrier to coffee products whose roast and ground coffee aroma is desired to be increased.
Yet another object of this invention is to provide aroma-enhanced instant coffee products which will retain the added aroma without intensity loss of character change, because of a suitable surface structure.
The method of accomplishing these and other objects will be apparent from the following detailed description of the invention.